Sheet Folder, Post-Processing Apparatus, Image Forming Apparatus, and Image Forming System

This patent application is based on and claims priority pursuant to 35 U.S.C. § 119 (a) to Japanese Patent Application Nos. 2024-066901, filed on Apr. 17, 2024, and 2025-006398, filed on Jan. 16, 2025, in the Japan Patent Office, the entire disclosure of each of which is hereby incorporated by reference herein.

Embodiments of the present disclosure relate to a sheet folder, a post-processing apparatus, an image forming apparatus, and an image forming system.

Sheet folders are known that sheets are folded and overlaid by changing rotations of a roller that conveys the sheets, and the thus overlaid sheets are ejected.

Different sheet folders are known that a fold line in one direction is formed in a sheet and the sheet is ejected, and a user folds the ejected sheet along the fold line formed as above to generate a booklet.

However, the above-described sheet folder has a limitation in the maximum number of sheets foldable in one operation, and the above-described different sheet folder is not likely to form fold lines with various folding operations.

Embodiments of the present disclosure described herein provide a novel sheet folder including a conveyance roller pair, a first folding roller, a second folding roller, a third folding roller, a guide, and circuitry. The conveyance roller pair conveys a sheet in a conveyance direction at a first speed. The first folding roller is disposed downstream from the conveyance roller pair in the conveyance direction. The second folding roller is in contact with the first folding roller to form a first nip with the first folding roller. The second folding roller rotates along with the first folding roller. The third folding roller is in contact with the first folding roller to form a second nip with the first folding roller. The third folding roller rotates along with the first folding roller. The guide is disposed between the conveyance roller pair and the first nip in the conveyance direction. The guide is changeable between a first posture to guide the sheet from the conveyance roller pair to the first nip and a second posture to guide the sheet from the conveyance roller pair to the second nip. The circuitry is to control the guide at the first posture to guide the sheet from the conveyance roller pair to the first nip, control the guide to change the posture from the first posture to the second posture to fold the sheet into the second nip while the first nip nips the sheet, and control the first folding roller to rotate at a second speed faster than the first speed of the conveyance roller pair while the second nip nips and folds the sheet.

Further, embodiments of the present disclosure described herein provide a post-processing apparatus including the above-described sheet folder, and a sheet binder to bundle multiple sheets including the sheet provided with a fold line folded by the sheet folder.

Further, embodiments of the present disclosure described herein provide an image forming apparatus including an image forming device to form an image on a sheet, and the above-described sheet folder to provide a fold line on the sheet on which the image is formed by the image forming device.

Further, embodiments of the present disclosure described herein provide an image forming system including an image forming apparatus, a conveyance roller pair, a first folding roller, a second folding roller, a third folding roller, a guide, and circuitry. The image forming apparatus forms an image on a sheet. The conveyance roller pair conveys a sheet in a conveyance direction of the sheet that has passed the image forming apparatus at a first speed. The first folding roller is disposed downstream from the conveyance roller pair in the conveyance direction. The second folding roller is in contact with the first folding roller to form a first nip with the first folding roller. The second folding roller rotates along with the first folding roller. The third folding roller is in contact with the first folding roller to form a second nip with the first folding roller. The third folding roller rotates along with the first folding roller. The guide is disposed between the conveyance roller pair and the first nip in the conveyance direction to change a posture between a first posture that guides the sheet to the first nip and a second posture that guides the sheet to the second nip. The circuitry is to control the guide at the first posture to guide the sheet from the conveyance roller pair to the first nip, control the guide to change the posture from the first posture to the second posture to fold the sheet into the second nip while the first nip nips the sheet, and control the first folding roller to rotate at a second speed faster than the first speed of the conveyance roller pair while the second nip nips and folds the sheet.

Further, embodiments of the present disclosure described herein provide a sheet folder including a conveyance roller pair, a first folding roller, a second folding roller, a third folding roller, and a guide. The conveyance roller pair conveys a sheet in a conveyance direction at a first speed. The first folding roller is disposed downstream from the conveyance roller pair in the conveyance direction. The second folding roller is in contact with the first folding roller to form a first nip with the first folding roller. The second folding roller rotates along with the first folding roller. The third folding roller is in contact with the first folding roller to form a second nip with the first folding roller. The third folding roller rotates along with the first folding roller. The guide is disposed downstream from the conveyance roller pair in the conveyance direction, and has a first guide face facing a first face of the sheet and a second guide face facing a second face of the sheet. The guide is changeable between a first posture to guide the sheet from the conveyance roller pair to the first nip and a second posture that guides the sheet from the conveyance roller pair to the second nip. The guide is to guide the sheet at the first posture from the conveyance roller pair to the first nip, and change the posture from the first posture to the second posture to fold the sheet into the second nip while the first nip nips the sheet; or guide the sheet at the first posture from the conveyance roller pair to the second nip, and change the posture from the second posture to the first posture to fold the sheet into the first nip while the second nip nips the sheet.

Further, embodiments of the present disclosure described herein provide an image forming apparatus including an image forming device to form an image on a sheet, and the above-described sheet folder to provide a fold line on the sheet on which the image is formed by the image forming device.

The accompanying drawings are intended to depict embodiments of the present disclosure and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. Also, identical or similar reference numerals designate identical or similar components throughout the several views.

In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that have a similar function, operate in a similar manner, and achieve a similar result.

Referring now to the drawings, embodiments of the present disclosure are described below. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

A description is provided of an image forming apparatusaccording to embodiments of the present disclosure with reference to the drawings.

is an external views of the image forming apparatus. The image forming apparatusforms an image on a sheet S (typically, a paper sheet).

As illustrated in, the image forming apparatusincludes a housingand an image forming device.

The housinghas a box shape to form an internal space for accommodating components of the image forming apparatus. The housinghas an in-body spacethat is accessible from the outside of the image forming apparatus. The in-body spaceis located, for example, slightly above the center of the housingin the vertical direction. The in-body spaceis exposed to the outside by cutting out the outer wall of the housing. The in-body spaceaccommodates a sheet folding unitas a sheet folder, a sheet binding unitas a post-processing device and a sheet binder, and a punching unit(see) that is described below.

The image forming deviceforms an image on a sheet S contained in a tray and ejects the sheet S on which the image is formed, to the sheet folding unit, the sheet binding unit, or the punching unit. The image forming devicemay include an inkjet image forming device that forms an image with ink or an electrophotographic image forming device that forms an image with toner. Since the image forming deviceofhas a known configuration, a detailed description of the configuration and functions of the image forming deviceis omitted.

The sheet folding unitis in the in-body spaceof the image forming apparatusand is disposed downstream from the image forming deviceand upstream from the sheet binding unitin a conveyance direction of the sheet in a conveyance path of the sheet S from the image forming deviceto the outside of the image forming apparatus. The conveyance path is indicated by a broken line and an arrow in. In other words, the sheet S on which the image is formed by the image forming deviceis first conveyed to the sheet folding unitto be subjected to a fold-line forming operation or a sheet folding operation described below, and subsequently conveyed to the sheet binding unitto be subjected to a sheet binding operation process described below.

The sheet folding unitis detachably attached to the image forming apparatus. After the sheet folding unitis detached from the image forming apparatus, the sheet S on which the image is formed by the image forming deviceis directly conveyed to the sheet binding unitto be subjected to the sheet binding operation. Alternatively, the punching unitmay be detachably attached to the position of the in-body spacefrom which the sheet folding unitis detached. After the punching unitis attached, the sheet S on which the image is formed by the image forming deviceis first conveyed to the punching unitto be subjected to a punching operation described below, and then conveyed to the sheet binding unitto be subjected to the sheet binding operation. Any unit to perform any operation on the sheet S including a punching unit is attachable at the position where the sheet folding unitis detached from the in-body space.

is a diagram illustrating an internal configuration of each of the sheet folding unitand the sheet binding unit.

is a diagram illustrating a configuration of the sheet folding unitwhen the guide plateis in a first posture.

is a diagram illustrating a configuration of the sheet folding unitwhen the guide plateis in a second posture.

is a perspective view of the guide plate.

is a diagram illustrating the sheet folding unitas viewed from a thickness direction of the sheet S on the main conveyance path Ph.

Each of the sheet folding unitand the sheet binding unitis manufactured as a unit and has an input interface and an output interface that can be connected to each other to convey the sheet S. In other words, the input interface IN of the sheet folding unitis connectable to an output interface of the image forming device. The input interface of the sheet binding unitis connectable to the output interface of the image forming deviceand the output interface OUT of the sheet folding unit.

The sheet folding unitperforms a sheet folding operation to form a given shape (e.g., Z-fold, letter fold-out, and half-fold) on a sheet S on which an image is formed by the image forming device, and a fold-line forming operation to form various fold lines on the sheet S. As illustrated in, the sheet folding unitincludes a housing, a conveyance roller pair, a first folding roller, a second folding roller, a third folding roller, a guide plateas a guide, a first stopperand a second stopper, a first sensor, a second sensorand a third sensor, and a driving force transmission mechanism. The first sensor, the second sensorand the third sensormay be referred to collectively as sheet sensors,and

The housinghas a box shape to form an internal space for accommodating components of the sheet folding unit. In addition, a main conveyance path Phand a return conveyance path Ph, which are spaces through which the sheet S passes, are formed in the internal space of the housing. The main conveyance path Phis a conveyance path from the input interface IN coupled to the image forming deviceto the output interface OUT coupled to the sheet binding unit. In the following description, a direction from the input interface IN to the output interface OUT on the main conveyance path Phis referred to as a “conveyance direction”. The return conveyance path Phis an annular conveyance path that branches from the main conveyance path Phat a branching portion A and joins the main conveyance path Phat a joining portion B. The joining portion B is located upstream from the branching portion A in the conveyance direction.

The conveyance roller pairconveys the sheet S along the main conveyance path Phin the conveyance direction. The conveyance roller pairincludes a drive rollerand a driven rollerfacing each other across the main conveyance path Phand are arranged upstream from the branching portion A in the conveyance direction and downstream from the joining portion B in the conveyance direction. The conveyance roller pairincludes the drive rollerand the driven rollerbetween the branching portion A and the joining portion B. The drive rollerand the driven rollerare rotatably supported by the housing. In response to a transmission of the driving force of the conveyance motor, the drive rolleris driven in a forward rotation, in other words, is rotated in a forward direction that is the conveyance direction of the sheet S (clockwise direction of). The driven rolleris disposed facing the drive rolleracross the main conveyance path Phand is driven by the rotation of the drive roller. As the conveyance motoris driven with the drive rollerand the driven rollernipping the sheet S, the sheet S is conveyed in the conveyance direction along the main conveyance path Ph.

The first folding rolleris disposed downstream from the conveyance roller pairin the conveyance direction. The first folding rolleris rotatably supported by the housingat a position facing both the main conveyance path Phand the return conveyance path Ph. The second folding rolleris rotatably supported by the housingat a position facing the main conveyance path Ph. The third folding rolleris rotatably supported by the housingat a position facing the return conveyance path Ph.

The first folding rollerand the second folding rollerare disposed to face each other across the main conveyance path Phand are downstream from the branching portion A in the conveyance direction. Further, the first folding rollerand the third folding rollerare disposed between the branching portion A and the joining portion B to face each other across the return conveyance path Ph.

As the driving force of a folder motoris transmitted to the first folding roller, the first folding rollerrotates in forward and reverse directions. The rotation in the forward direction of the first folding rolleris a rotation in a direction to convey the sheet S on the main conveyance path Phin the conveyance direction of the sheet S (counterclockwise direction in). The rotation in the reverse direction of the first folding rolleris a rotation in a direction opposite to the direction of the forward rotation. The folder motoris rotatable in forward and reverse directions to rotate the first folding rollerin forward and reverse directions. The second folding rollerand the third folding rollerare rotated together with the rotation of the first folding roller.

The first folding rollerand the second folding rollerform a first nip region Nin which the sheet S on the main conveyance path Phis nipped. The first folding rollerand the third folding rollerform a second nip region Nin which the sheet S on the return conveyance path Phis nipped. The action “nip” indicates that a sheet S is sandwiched by the force that can convey the sheet S by a rotation of a pair of rollers.

The guide plateis disposed between the conveyance roller pairand the first folding rolleron the main conveyance path Ph. In other words, the guide plateis disposed downstream from the conveyance roller pairin the conveyance direction and upstream from the first folding rollerin the conveyance direction. The guide plateis rotatably supported by the housingin the vicinity of the branching portion A. The guide plateis rotatable (changeable) between the first posture illustrated inand the second posture illustrated indue to the transmission of the driving force of a guide motor

Further, as illustrated in, the guide platehas a slitthrough which the sheet S passes. The guide platechanges the destination of conveyance of the sheet S. The slitis formed between a pair of guide faces including guide facesandas a first guide face and a second guide face. The guide facesandare disposed facing each other across the main conveyance path Phat an interval having a distance through which the sheet S can pass. The guide facesandguide the sheet S that is conveyed by the conveyance roller pairon the main conveyance path Phin the conveyance direction. The interval of the guide facesandhas an upstream side in the conveyance direction greater than a downstream side in the conveyance direction.

The first posture is a posture of the guide platein which the sheet S conveyed by the conveyance roller pairto the first nip region Nand the sheet S is allowed to be conveyed from second nip region Nto the first nip region N. The second posture is a posture of the guide platein which the sheet S conveyed by the conveyance roller pairto the second nip region Nand the sheet S is allowed to be conveyed from the first nip region Nto the second nip region N.

For example, as the conveyance roller pairand the first folding rollerare rotated in the forward direction in the first posture of the guide platebefore the leading end of the sheet S (the downstream end in the conveyance direction) reaches the guide plate, the sheet S conveyed by the conveyance roller pairpasses the first nip region Nthrough the slitof the guide platein the first posture, in other words, the sheet S is conveyed in the conveyance direction on the main conveyance path Ph.

As another example, as the conveyance roller pairis rotated in the forward direction and the first folding rolleris rotated in the reverse direction with the guide platein the second posture before the leading end of the sheet S reaches the guide plate, the sheet S by the conveyance roller pairpasses the second nip region Nthrough the slitof the guide platein the second posture, in other words, the sheet S is conveyed to the return conveyance path Phthrough the branching portion A.

As yet another example, as illustrated in, as the first folding rolleris driven in the reverse rotation while changing the guide platefrom the first posture to second posture with the sheet S nipped by the conveyance roller pairand the first nip region N, the sheet S passes the second nip region Nwith a folding position C(see) of the sheet S as the leading end of the sheet S. In other words, when the guide plateis changed from the first posture to the second posture and then the first folding rolleris rotated in the reverse direction, with the sheet S nipped by the first nip region N, the sheet S is folded in the second nip region N. Due to this operation, as illustrated in, the sheet S is folded in at the folding position C.

As yet another example, as illustrated in, as the first folding rolleris rotated in the forward direction while changing the guide platefrom the second posture to the first posture with the sheet S nipped by the conveyance roller pairand the second nip region N, the sheet S passes through the first nip region Nwith a folding position C(see) of the sheet S as the leading end of the sheet S. In other words, when the guide plateis changed from the second posture to the first posture and then the first folding rolleris rotated in the forward direction, with the sheet S nipped by the second nip region N, the sheet S is folded in the first nip region N. Due to this operation, as illustrated in, the sheet S is folded outward at the folding position C.

is a diagram illustrating a variation of folding positions of a sheet.

is a diagram illustrating another variation of folding positions of a sheet.

The “folding position” is any position between the leading end and the trailing end of a sheet S in the conveyance direction. The trailing end of a sheet S indicates an end on the upstream side of the sheet S in the conveyance direction). The sheet folding unitforms fold lines, each of which passes the folding position and is unfolded in the width direction of the sheet S. The width direction of the sheet S is a direction orthogonal to the conveyance direction of the sheet S. The “fold-in” is a folding type that a valley fold is performed on the surface of the sheet S on which an image is formed by the image forming device(the top face of the sheet S facing the drive rollerin). The “fold-out” is a folding type that a mountain fold is performed on the surface of the sheet S.

For example, as illustrated in, as the sheet S is folded inward at the folding position Cat the center of the sheet S in the conveyance direction, a fold line for half-fold can be applied to the sheet S. Further, as the sheet S is folded inward at the folding position Cthat is located one third from the leading end of the sheet S in the conveyance direction and further folded inward at a folding position Cthat is located one third from the trailing end of the sheet S in the conveyance direction, the fold lines for letter fold-in can be applied to the sheet S. Further, as the sheet S is folded outward at the folding position Cand further folded inward at the folding position C, the fold lines for letter fold-out can be applied to the sheet S. Further, as the sheet S is folded outward at the folding position Cand further folded inward at a folding position Cthat is located one fourth from the trailing end of the sheet S, the fold lines for Z-fold can be applied to the sheet S.

Further, as illustrated in, the folding positions of multiple sheets S sequentially supplied to the sheet folding unitmay be shifted in the conveyance direction. More specifically, when the multiple sheets S are bundled to perform the letter fold-in operation, the interval (first interval) may be narrower toward the sheet S placed inside in the folded bundle of all the intervals between the folding position Cand the folding position Cof the multiple sheets S of the sheet bundle, so that the interval (third interval) may be wider toward the sheet S placed outside in the folded bundle of all the intervals between the folding position Cand the folding position Cof the multiple sheets S of the sheet bundle. The relation between the folding type of the sheet S and the folding position of the sheet S is stored in advance in a hard disk drive (HDD)(see). Further, the variation of fold lines applicable by the sheet folding unitis not limited to the examples of.

As illustrated in, the first stoppercontacts the guide platein the first posture to prevent the guide platefrom rotating in a direction away from the second posture (clockwise direction in). As illustrated in, the second stoppercontacts the guide platein the second posture to prevent the guide platefrom rotating in a direction away from the first posture (counterclockwise direction in). Due to such configurations as described above, the guide platerotates between the first posture and the second posture only, in other words, between the first stopperand the second stopperonly). In other words, the first stopperand the second stopperrestrict the rotation range of the guide plate.

The sheet sensors,andare disposed facing the main conveyance path Phor the return conveyance path Ph. The sheet sensors,anddetect the sheet S to face installation positions where the sheet sensors,andare disposed, and output respective detection signals to a controllerthat is described below. More specifically, each of the sheet sensors,andoutputs a detection signal when the sheet S is brought to the position to face the installation position of each of the sheet sensors,and(ON), and stops the output of the detection signal when the sheet S is not at the position (OFF). Any detailed example of the sheet sensors,andis not limited to any sensor but a sensor may be, for example, a reflection-type optical sensor.

The first sensoris disposed facing the main conveyance path Phand upstream from the conveyance roller pairin the conveyance direction. The first sensordetects the sheet S that is conveyed from the image forming devicetoward the conveyance roller pair. The second sensoris disposed facing the main conveyance path Phand downstream from the first nip region Nin the conveyance direction.

The second sensordetects the sheet S that passes the first nip region Nto be ejected to the sheet binding unit. The third sensoris disposed facing the return conveyance path Phand closer to the joining portion B from the second nip region N. The third sensordetects the sheet S that passes the second nip region Ntoward the joining portion B on the return conveyance path Ph.